1. Field of the Invention
The present invention relates to a thin film magnetic head structure and a method of fabricating the same, and more particularly, it relates to a thin film magnetic head structure which is characterized in its terminal connection structure, and a method of fabricating the same.
2. Description of the Background Art
In relation to a magnetic recording apparatus which has recently been increased in capacity and decreased in size, a magnetic head is desired having high recording density and a multi-track function. In order to increase the number of tracks, it is necessary to reduce widths of the respective tracks, as well as those of terminals provided in the magnetic head. Thus, spaces between adjacent terminals are reduced and a terminal extracting portion must be increased in connection accuracy.
A description is now made on connection in a terminal extraction portion of a conventional thin film magnetic head structure.
FIG. 26 is a plan view showing terminal connection in a conventional thin film magnetic head structure, and FIG. 27 is a sectional view taken along the line IV--IV in FIG. 26.
Referring to FIGS. 26 and 27, the conventional thin film magnetic head structure includes a flexible printed board 510, a thin film magnetic head portion 520 and a support plate 530. The flexible printed board 510 is formed by a number of lead terminals 502, a base film 503 and a cover film 504. The lead terminals 502 are arranged on the surface of the base film 503, which is made of polyimide. The lead terminals 502 are formed of copper foil members and Au layers which are formed on the copper foil members by plating. The cover film 504 is so bonded onto the surfaces of the lead terminals 502 as to partially expose the lead terminals 502.
The thin film magnetic head portion 520 is formed by external connection terminals 511, a magnetic substrate 512, an element portion 513 and a protective plate 514. The element portion 513 is formed on a surface of the magnetic substrate 512, which is close to a medium sliding surface 519 for sliding movement of a magnetic medium such as a tape. The external connection terminals 511c are electrically connected with the element portion 513, to extend on the surface of the magnetic substrate 512 toward the other end. Two such external connection terminals 511a and 511b are extracted from each element, so that the first terminal 511a, serving as an externally connected terminal, is provided with a wide externally extracted pattern 511c on its forward end, while the other terminal 511b is grounded. The protective plate 514, which is made of ferrite, glass or the like, is bonded onto the surface of the element portion 513. The medium sliding surface 519, which is defined by the magnetic substrate 512, the element portion 513 and the protective plate 514, has arbitrary curvature.
The base film 503 of the flexible printed board 510 and the magnetic substrate 512 of the thin film magnetic head portion 520 are bonded onto the support plate 530. In such a bonding step, the flexible printed board 510 and the thin film magnetic head portion 520 must be located on the support plate 530 at a high accuracy, in order to oppose the lead terminals 502 and the external connection terminals 511 to be connected with each other. The lead terminals 502 are electrically connected with the corresponding external connection terminals 511 through wires 501, which are made of Au, Al or the like, by a terminal connection method utilizing a wire bonding technique. In more specific terms, the wires 501 are compression-bonded to the terminals 502 and 511, with the application of ultrasonic vibration.
The conventional thin film magnetic head structure is formed in the aforementioned manner.
A method of fabricating the conventional thin film magnetic head structure is now described.
First, a number of groups of lead terminals for forming flexible printed boards are formed on a sheet-type film. Then, the sheet-type film is punched out to form a number of flexible printed boards including film parts and the lead terminals. Each of the flexible printed boards is located on and bonded to a support plate with a thin film magnetic head portion. Then, the lead terminals are electrically connected with external connection terminals provided on the thin film magnetic head portion by wire bonding. Thereafter the lead terminals, the external connection terminals, wires and the like are sealed by molding.
The conventional thin film magnetic head structure is fabricated in the aforementioned manner.
In the aforementioned conventional thin film magnetic head structure, the lead terminals 502 are electrically connected with the corresponding external connection terminals 511 by the wires 501. In this case, both ends of the wires 501 must be employed for connecting the terminals with each other. Thus, complicated wire bonding operations are disadvantageously required in a number of portions.
In order to automate the wire bonding step, on the other hand, it is necessary to bond the flexible printed board 510 and the thin film magnetic head portion 520 onto the support plate 530 in advance. Further, bonding must be done after the flexible printed board 510 and the thin film magnetic head portion 520 are located highly precisely.
When the flexible printed board 510 is bonded onto the support plate 530, bubbles may enter the bonded portion, to disadvantageously absorb ultrasonic waves in the wire bonding step. In this case, it is difficult to sufficiently bond the wires 501 with the lead terminals 502 since the ultrasonic waves are not transferred to the lead terminals 502. Thus, bondability between the wires 501 and the lead terminals 502 is reduced.
Further, the wire bonding step requires a temperature of about 150.degree. C., which may soften a binder for bonding the lead terminals 502 to the base film 503. When the binder is thus softened, the ultrasonic waves are absorbed by the base film 503 in the wire bonding step. Thus, the ultrasonic waves are so insufficiently transferred to the lead terminals 502 that bondability is reduced between the wires 501 and the lead terminals 502. Therefore, the wire bonding step must be carried out under a relatively low temperature with difficulty in selection of bonding conditions, leading to extremely small and unstable margins for such condition setting.
In addition, the flexible printed board 510 forming the thin film magnetic head structure is bonded onto the support plate 530 after the same is punched out from a sheet-type film. Thus, the step of bonding each flexible printed board 510 onto the support plate 530 is so extremely complicated that it is difficult to automate the fabrication steps.